# uncompyle6 version 3.2.3
# Python bytecode 3.6 (3379)
# Decompiled from: Python 3.6.8 |Anaconda custom (64-bit)| (default, Feb 21 2019, 18:30:04) [MSC v.1916 64 bit (AMD64)]
# Embedded file name: site-packages\sqlalchemy\engine\default.py
"""Default implementations of per-dialect sqlalchemy.engine classes.

These are semi-private implementation classes which are only of importance
to database dialect authors; dialects will usually use the classes here
as the base class for their own corresponding classes.

"""
import re, random
from . import reflection, interfaces, result
from ..sql import compiler, expression, schema
from .. import types as sqltypes
from .. import exc, util, pool, processors
import codecs, weakref
from .. import event

AUTOCOMMIT_REGEXP = re.compile(
    "\\s*(?:UPDATE|INSERT|CREATE|DELETE|DROP|ALTER)", re.I | re.UNICODE
)
SERVER_SIDE_CURSOR_RE = re.compile("\\s*SELECT", re.I | re.UNICODE)


class DefaultDialect(interfaces.Dialect):
    """Default implementation of Dialect"""

    statement_compiler = compiler.SQLCompiler
    ddl_compiler = compiler.DDLCompiler
    type_compiler = compiler.GenericTypeCompiler
    preparer = compiler.IdentifierPreparer
    supports_alter = True
    supports_comments = False
    inline_comments = False
    default_sequence_base = 1
    execute_sequence_format = tuple
    supports_views = True
    supports_sequences = False
    sequences_optional = False
    preexecute_autoincrement_sequences = False
    postfetch_lastrowid = True
    implicit_returning = False
    supports_right_nested_joins = True
    supports_native_enum = False
    supports_native_boolean = False
    supports_simple_order_by_label = True
    engine_config_types = util.immutabledict(
        [
            ("convert_unicode", util.bool_or_str("force")),
            ("pool_timeout", util.asint),
            ("echo", util.bool_or_str("debug")),
            ("echo_pool", util.bool_or_str("debug")),
            ("pool_recycle", util.asint),
            ("pool_size", util.asint),
            ("max_overflow", util.asint),
            ("pool_threadlocal", util.asbool),
        ]
    )
    supports_native_decimal = False
    if util.py3k:
        supports_unicode_statements = True
        supports_unicode_binds = True
        returns_unicode_strings = True
        description_encoding = None
    else:
        supports_unicode_statements = False
        supports_unicode_binds = False
        returns_unicode_strings = False
        description_encoding = "use_encoding"
    name = "default"
    max_identifier_length = 9999
    max_index_name_length = None
    supports_sane_rowcount = True
    supports_sane_multi_rowcount = True
    colspecs = {}
    default_paramstyle = "named"
    supports_default_values = False
    supports_empty_insert = True
    supports_multivalues_insert = False
    supports_server_side_cursors = False
    server_version_info = None
    construct_arguments = None
    requires_name_normalize = False
    reflection_options = ()
    dbapi_exception_translation_map = util.immutabledict()

    def __init__(
        self,
        convert_unicode=False,
        encoding="utf-8",
        paramstyle=None,
        dbapi=None,
        implicit_returning=None,
        supports_right_nested_joins=None,
        case_sensitive=True,
        supports_native_boolean=None,
        empty_in_strategy="static",
        label_length=None,
        **kwargs
    ):
        if not getattr(self, "ported_sqla_06", True):
            util.warn("The %s dialect is not yet ported to the 0.6 format" % self.name)
        self.convert_unicode = convert_unicode
        self.encoding = encoding
        self.positional = False
        self._ischema = None
        self.dbapi = dbapi
        if paramstyle is not None:
            self.paramstyle = paramstyle
        else:
            if self.dbapi is not None:
                self.paramstyle = self.dbapi.paramstyle
            else:
                self.paramstyle = self.default_paramstyle
            if implicit_returning is not None:
                self.implicit_returning = implicit_returning
            self.positional = self.paramstyle in ("qmark", "format", "numeric")
            self.identifier_preparer = self.preparer(self)
            self.type_compiler = self.type_compiler(self)
            if supports_right_nested_joins is not None:
                self.supports_right_nested_joins = supports_right_nested_joins
            if supports_native_boolean is not None:
                self.supports_native_boolean = supports_native_boolean
            self.case_sensitive = case_sensitive
            self.empty_in_strategy = empty_in_strategy
        if empty_in_strategy == "static":
            self._use_static_in = True
        else:
            if empty_in_strategy in ("dynamic", "dynamic_warn"):
                self._use_static_in = False
                self._warn_on_empty_in = empty_in_strategy == "dynamic_warn"
            else:
                raise exc.ArgumentError(
                    "empty_in_strategy may be 'static', 'dynamic', or 'dynamic_warn'"
                )
            if label_length:
                if label_length > self.max_identifier_length:
                    raise exc.ArgumentError(
                        "Label length of %d is greater than this dialect's maximum identifier length of %d"
                        % (label_length, self.max_identifier_length)
                    )
            self.label_length = label_length
            if self.description_encoding == "use_encoding":
                self._description_decoder = processors.to_unicode_processor_factory(
                    encoding
                )
            else:
                if self.description_encoding is not None:
                    self._description_decoder = processors.to_unicode_processor_factory(
                        self.description_encoding
                    )
            self._encoder = codecs.getencoder(self.encoding)
            self._decoder = processors.to_unicode_processor_factory(self.encoding)

    @util.memoized_property
    def _type_memos(self):
        return weakref.WeakKeyDictionary()

    @property
    def dialect_description(self):
        return self.name + "+" + self.driver

    @property
    def supports_sane_rowcount_returning(self):
        return self.supports_sane_rowcount

    @classmethod
    def get_pool_class(cls, url):
        return getattr(cls, "poolclass", pool.QueuePool)

    def initialize(self, connection):
        try:
            self.server_version_info = self._get_server_version_info(connection)
        except NotImplementedError:
            self.server_version_info = None

        try:
            self.default_schema_name = self._get_default_schema_name(connection)
        except NotImplementedError:
            self.default_schema_name = None

        try:
            self.default_isolation_level = self.get_isolation_level(
                connection.connection
            )
        except NotImplementedError:
            self.default_isolation_level = None

        self.returns_unicode_strings = self._check_unicode_returns(connection)
        if self.description_encoding is not None:
            if self._check_unicode_description(connection):
                self._description_decoder = self.description_encoding = None
        self.do_rollback(connection.connection)

    def on_connect(self):
        """return a callable which sets up a newly created DBAPI connection.
        
        This is used to set dialect-wide per-connection options such as
        isolation modes, unicode modes, etc.
        
        If a callable is returned, it will be assembled into a pool listener
        that receives the direct DBAPI connection, with all wrappers removed.
        
        If None is returned, no listener will be generated.
        
        """
        pass

    def _check_unicode_returns(self, connection, additional_tests=None):
        if util.py2k:
            if not self.supports_unicode_statements:
                cast_to = util.binary_type
            cast_to = util.text_type
        if self.positional:
            parameters = self.execute_sequence_format()
        else:
            parameters = {}

        def check_unicode(test):
            statement = cast_to(expression.select([test]).compile(dialect=self))
            try:
                cursor = connection.connection.cursor()
                connection._cursor_execute(cursor, statement, parameters)
                row = cursor.fetchone()
                cursor.close()
            except exc.DBAPIError as de:
                util.warn("Exception attempting to detect unicode returns: %r" % de)
                return False
            else:
                return isinstance(row[0], util.text_type)

        tests = [
            expression.cast(
                expression.literal_column("'test plain returns'"), sqltypes.VARCHAR(60)
            ),
            expression.cast(
                expression.literal_column("'test unicode returns'"),
                sqltypes.Unicode(60),
            ),
        ]
        if additional_tests:
            tests += additional_tests
        results = {check_unicode(test) for test in tests}
        if results.issuperset([True, False]):
            return "conditional"
        else:
            return results == {True}

    def _check_unicode_description(self, connection):
        if util.py2k:
            if not self.supports_unicode_statements:
                cast_to = util.binary_type
            cast_to = util.text_type
        cursor = connection.connection.cursor()
        try:
            cursor.execute(
                cast_to(
                    expression.select(
                        [expression.literal_column("'x'").label("some_label")]
                    ).compile(dialect=self)
                )
            )
            return isinstance(cursor.description[0][0], util.text_type)
        finally:
            cursor.close()

    def type_descriptor(self, typeobj):
        """Provide a database-specific :class:`.TypeEngine` object, given
        the generic object which comes from the types module.
        
        This method looks for a dictionary called
        ``colspecs`` as a class or instance-level variable,
        and passes on to :func:`.types.adapt_type`.
        
        """
        return sqltypes.adapt_type(typeobj, self.colspecs)

    def reflecttable(self, connection, table, include_columns, exclude_columns, **opts):
        insp = reflection.Inspector.from_engine(connection)
        return insp.reflecttable(table, include_columns, exclude_columns, **opts)

    def get_pk_constraint(self, conn, table_name, schema=None, **kw):
        """Compatibility method, adapts the result of get_primary_keys()
        for those dialects which don't implement get_pk_constraint().
        
        """
        return {"constrained_columns": self.get_primary_keys(schema=schema, **kw)}

    def validate_identifier(self, ident):
        if len(ident) > self.max_identifier_length:
            raise exc.IdentifierError(
                "Identifier '%s' exceeds maximum length of %d characters"
                % (ident, self.max_identifier_length)
            )

    def connect(self, *cargs, **cparams):
        return self.dbapi.connect(*cargs, **cparams)

    def create_connect_args(self, url):
        opts = url.translate_connect_args()
        opts.update(url.query)
        return [[], opts]

    def set_engine_execution_options(self, engine, opts):
        if "isolation_level" in opts:
            isolation_level = opts["isolation_level"]

            @event.listens_for(engine, "engine_connect")
            def set_isolation(connection, branch):
                if not branch:
                    self._set_connection_isolation(connection, isolation_level)

        if "schema_translate_map" in opts:
            getter = schema._schema_getter(opts["schema_translate_map"])
            engine.schema_for_object = getter

            @event.listens_for(engine, "engine_connect")
            def set_schema_translate_map(connection, branch):
                connection.schema_for_object = getter

    def set_connection_execution_options(self, connection, opts):
        if "isolation_level" in opts:
            self._set_connection_isolation(connection, opts["isolation_level"])
        if "schema_translate_map" in opts:
            getter = schema._schema_getter(opts["schema_translate_map"])
            connection.schema_for_object = getter

    def _set_connection_isolation(self, connection, level):
        if connection.in_transaction():
            util.warn(
                "Connection is already established with a Transaction; setting isolation_level may implicitly rollback or commit the existing transaction, or have no effect until next transaction"
            )
        self.set_isolation_level(connection.connection, level)
        connection.connection._connection_record.finalize_callback.append(
            self.reset_isolation_level
        )

    def do_begin(self, dbapi_connection):
        pass

    def do_rollback(self, dbapi_connection):
        dbapi_connection.rollback()

    def do_commit(self, dbapi_connection):
        dbapi_connection.commit()

    def do_close(self, dbapi_connection):
        dbapi_connection.close()

    @util.memoized_property
    def _dialect_specific_select_one(self):
        return str(expression.select([1]).compile(dialect=self))

    def do_ping(self, dbapi_connection):
        cursor = None
        try:
            cursor = dbapi_connection.cursor()
            try:
                cursor.execute(self._dialect_specific_select_one)
            finally:
                cursor.close()

        except self.dbapi.Error as err:
            if self.is_disconnect(err, dbapi_connection, cursor):
                return False
            raise
        else:
            return True

    def create_xid(self):
        """Create a random two-phase transaction ID.
        
        This id will be passed to do_begin_twophase(), do_rollback_twophase(),
        do_commit_twophase().  Its format is unspecified.
        """
        return "_sa_%032x" % random.randint(0, 340282366920938463463374607431768211456)

    def do_savepoint(self, connection, name):
        connection.execute(expression.SavepointClause(name))

    def do_rollback_to_savepoint(self, connection, name):
        connection.execute(expression.RollbackToSavepointClause(name))

    def do_release_savepoint(self, connection, name):
        connection.execute(expression.ReleaseSavepointClause(name))

    def do_executemany(self, cursor, statement, parameters, context=None):
        cursor.executemany(statement, parameters)

    def do_execute(self, cursor, statement, parameters, context=None):
        cursor.execute(statement, parameters)

    def do_execute_no_params(self, cursor, statement, context=None):
        cursor.execute(statement)

    def is_disconnect(self, e, connection, cursor):
        return False

    def reset_isolation_level(self, dbapi_conn):
        self.set_isolation_level(dbapi_conn, self.default_isolation_level)


class StrCompileDialect(DefaultDialect):
    statement_compiler = compiler.StrSQLCompiler
    ddl_compiler = compiler.DDLCompiler
    type_compiler = compiler.StrSQLTypeCompiler
    preparer = compiler.IdentifierPreparer
    supports_sequences = True
    sequences_optional = True
    preexecute_autoincrement_sequences = False
    implicit_returning = False
    supports_native_boolean = True
    supports_simple_order_by_label = True


class DefaultExecutionContext(interfaces.ExecutionContext):
    isinsert = False
    isupdate = False
    isdelete = False
    is_crud = False
    is_text = False
    isddl = False
    executemany = False
    compiled = None
    statement = None
    result_column_struct = None
    returned_defaults = None
    _is_implicit_returning = False
    _is_explicit_returning = False
    _translate_colname = None
    _expanded_parameters = util.immutabledict()

    @classmethod
    def _init_ddl(cls, dialect, connection, dbapi_connection, compiled_ddl):
        """Initialize execution context for a DDLElement construct."""
        self = cls.__new__(cls)
        self.root_connection = connection
        self._dbapi_connection = dbapi_connection
        self.dialect = connection.dialect
        self.compiled = compiled = compiled_ddl
        self.isddl = True
        self.execution_options = compiled.execution_options
        if connection._execution_options:
            self.execution_options = dict(self.execution_options)
            self.execution_options.update(connection._execution_options)
        if not dialect.supports_unicode_statements:
            self.unicode_statement = util.text_type(compiled)
            self.statement = dialect._encoder(self.unicode_statement)[0]
        else:
            self.statement = self.unicode_statement = util.text_type(compiled)
        self.cursor = self.create_cursor()
        self.compiled_parameters = []
        if dialect.positional:
            self.parameters = [dialect.execute_sequence_format()]
        else:
            self.parameters = [{}]
        return self

    @classmethod
    def _init_compiled(
        cls, dialect, connection, dbapi_connection, compiled, parameters
    ):
        """Initialize execution context for a Compiled construct."""
        self = cls.__new__(cls)
        self.root_connection = connection
        self._dbapi_connection = dbapi_connection
        self.dialect = connection.dialect
        self.compiled = compiled
        if not compiled.can_execute:
            raise AssertionError
        self.execution_options = compiled.execution_options.union(
            connection._execution_options
        )
        self.result_column_struct = (
            compiled._result_columns,
            compiled._ordered_columns,
            compiled._textual_ordered_columns,
        )
        self.unicode_statement = util.text_type(compiled)
        if not dialect.supports_unicode_statements:
            self.statement = self.unicode_statement.encode(self.dialect.encoding)
        else:
            self.statement = self.unicode_statement
        self.isinsert = compiled.isinsert
        self.isupdate = compiled.isupdate
        self.isdelete = compiled.isdelete
        self.is_text = compiled.isplaintext
        if not parameters:
            self.compiled_parameters = [compiled.construct_params()]
        else:
            self.compiled_parameters = [
                compiled.construct_params(m, _group_number=grp)
                for grp, m in enumerate(parameters)
            ]
            self.executemany = len(parameters) > 1
        self.cursor = self.create_cursor()
        if self.isinsert or self.isupdate or self.isdelete:
            self.is_crud = True
            self._is_explicit_returning = bool(compiled.statement._returning)
            self._is_implicit_returning = bool(
                compiled.returning and not compiled.statement._returning
            )
        if self.compiled.insert_prefetch or self.compiled.update_prefetch:
            if self.executemany:
                self._process_executemany_defaults()
            else:
                self._process_executesingle_defaults()
            processors = compiled._bind_processors
            if compiled.contains_expanding_parameters:
                positiontup = self._expand_in_parameters(compiled, processors)
            else:
                if compiled.positional:
                    positiontup = self.compiled.positiontup
            parameters = []
            if compiled.positional:
                for compiled_params in self.compiled_parameters:
                    param = []
                    for key in positiontup:
                        if key in processors:
                            param.append(processors[key](compiled_params[key]))
                        else:
                            param.append(compiled_params[key])

                    parameters.append(dialect.execute_sequence_format(param))

            else:
                encode = not dialect.supports_unicode_statements
                for compiled_params in self.compiled_parameters:
                    if encode:
                        param = dict(
                            (
                                (
                                    dialect._encoder(key)[0],
                                    processors[key](compiled_params[key])
                                    if key in processors
                                    else compiled_params[key],
                                )
                                for key in compiled_params
                            )
                        )
                    else:
                        param = dict(
                            (
                                (
                                    key,
                                    processors[key](compiled_params[key])
                                    if key in processors
                                    else compiled_params[key],
                                )
                                for key in compiled_params
                            )
                        )
                    parameters.append(param)

            self.parameters = dialect.execute_sequence_format(parameters)
            return self

    def _expand_in_parameters(self, compiled, processors):
        """handle special 'expanding' parameters, IN tuples that are rendered
        on a per-parameter basis for an otherwise fixed SQL statement string.
        
        """
        if self.executemany:
            raise exc.InvalidRequestError(
                "'expanding' parameters can't be used with executemany()"
            )
        if self.compiled.positional:
            if self.compiled._numeric_binds:
                raise NotImplementedError(
                    "'expanding' bind parameters not supported with 'numeric' paramstyle at this time."
                )
        self._expanded_parameters = {}
        compiled_params = self.compiled_parameters[0]
        if compiled.positional:
            positiontup = []
        else:
            positiontup = None
        replacement_expressions = {}
        for name in (
            self.compiled.positiontup if compiled.positional else self.compiled.binds
        ):
            parameter = self.compiled.binds[name]
            if parameter.expanding:
                values = compiled_params.pop(name)
                if not values:
                    raise exc.InvalidRequestError(
                        "'expanding' parameters can't be used with an empty list"
                    )
                else:
                    if isinstance(values[0], (tuple, list)):
                        to_update = [
                            ("%s_%s_%s" % (name, i, j), value)
                            for i, tuple_element in enumerate(values, 1)
                            for j, value in iter(enumerate(tuple_element, 1))
                        ]
                        replacement_expressions[name] = (", ").join(
                            (
                                "(%s)"
                                % (", ").join(
                                    (
                                        self.compiled.bindtemplate
                                        % {
                                            "name": to_update[
                                                i * len(tuple_element) + j
                                            ][0]
                                        }
                                        for j, value in enumerate(tuple_element)
                                    )
                                )
                                for i, tuple_element in enumerate(values)
                            )
                        )
                    else:
                        to_update = [
                            ("%s_%s" % (name, i), value)
                            for i, value in enumerate(values, 1)
                        ]
                        replacement_expressions[name] = (", ").join(
                            (
                                self.compiled.bindtemplate % {"name": key}
                                for key, value in to_update
                            )
                        )
                    compiled_params.update(to_update)
                    processors.update(
                        (
                            (key, processors[name])
                            for key in to_update
                            if name in processors
                        )
                    )
                    if compiled.positional:
                        positiontup.extend((name for name, value in to_update))
                self._expanded_parameters[name] = [
                    expand_key for expand_key, value in to_update
                ]
            elif compiled.positional:
                positiontup.append(name)

        def process_expanding(m):
            return replacement_expressions.pop(m.group(1))

        self.statement = re.sub(
            "\\[EXPANDING_(\\S+)\\]", process_expanding, self.statement
        )
        return positiontup

    @classmethod
    def _init_statement(
        cls, dialect, connection, dbapi_connection, statement, parameters
    ):
        """Initialize execution context for a string SQL statement."""
        self = cls.__new__(cls)
        self.root_connection = connection
        self._dbapi_connection = dbapi_connection
        self.dialect = connection.dialect
        self.is_text = True
        self.execution_options = connection._execution_options
        if not parameters:
            if self.dialect.positional:
                self.parameters = [dialect.execute_sequence_format()]
            else:
                self.parameters = [{}]
        else:
            if isinstance(parameters[0], dialect.execute_sequence_format):
                self.parameters = parameters
            else:
                if isinstance(parameters[0], dict):
                    if dialect.supports_unicode_statements:
                        self.parameters = parameters
                    else:
                        self.parameters = [
                            {dialect._encoder(k)[0]: d[k] for k in d}
                            for d in parameters
                        ] or [{}]
                else:
                    self.parameters = [
                        dialect.execute_sequence_format(p) for p in parameters
                    ]
                self.executemany = len(parameters) > 1
                if not dialect.supports_unicode_statements:
                    if isinstance(statement, util.text_type):
                        self.unicode_statement = statement
                        self.statement = dialect._encoder(statement)[0]
                    self.statement = self.unicode_statement = statement
                self.cursor = self.create_cursor()
                return self

    @classmethod
    def _init_default(cls, dialect, connection, dbapi_connection):
        """Initialize execution context for a ColumnDefault construct."""
        self = cls.__new__(cls)
        self.root_connection = connection
        self._dbapi_connection = dbapi_connection
        self.dialect = connection.dialect
        self.execution_options = connection._execution_options
        self.cursor = self.create_cursor()
        return self

    @util.memoized_property
    def engine(self):
        return self.root_connection.engine

    @util.memoized_property
    def postfetch_cols(self):
        return self.compiled.postfetch

    @util.memoized_property
    def prefetch_cols(self):
        if self.isinsert:
            return self.compiled.insert_prefetch
        elif self.isupdate:
            return self.compiled.update_prefetch
        else:
            return ()

    @util.memoized_property
    def returning_cols(self):
        self.compiled.returning

    @util.memoized_property
    def no_parameters(self):
        return self.execution_options.get("no_parameters", False)

    @util.memoized_property
    def should_autocommit(self):
        autocommit = self.execution_options.get(
            "autocommit",
            not self.compiled
            and self.statement
            and expression.PARSE_AUTOCOMMIT
            or False,
        )
        if autocommit is expression.PARSE_AUTOCOMMIT:
            return self.should_autocommit_text(self.unicode_statement)
        else:
            return autocommit

    def _execute_scalar(self, stmt, type_):
        """Execute a string statement on the current cursor, returning a
        scalar result.
        
        Used to fire off sequences, default phrases, and "select lastrowid"
        types of statements individually or in the context of a parent INSERT
        or UPDATE statement.
        
        """
        conn = self.root_connection
        if isinstance(stmt, util.text_type):
            if not self.dialect.supports_unicode_statements:
                stmt = self.dialect._encoder(stmt)[0]
        if self.dialect.positional:
            default_params = self.dialect.execute_sequence_format()
        else:
            default_params = {}
        conn._cursor_execute(self.cursor, stmt, default_params, context=self)
        r = self.cursor.fetchone()[0]
        if type_ is not None:
            proc = type_._cached_result_processor(
                self.dialect, self.cursor.description[0][1]
            )
            if proc:
                return proc(r)
            return r

    @property
    def connection(self):
        return self.root_connection._branch()

    def should_autocommit_text(self, statement):
        return AUTOCOMMIT_REGEXP.match(statement)

    def _use_server_side_cursor(self):
        if not self.dialect.supports_server_side_cursors:
            return False
        else:
            if self.dialect.server_side_cursors:
                use_server_side = self.execution_options.get(
                    "stream_results", True
                ) and (
                    self.compiled
                    and isinstance(self.compiled.statement, expression.Selectable)
                    or (
                        not self.compiled
                        or isinstance(self.compiled.statement, expression.TextClause)
                    )
                    and self.statement
                    and SERVER_SIDE_CURSOR_RE.match(self.statement)
                )
            else:
                use_server_side = self.execution_options.get("stream_results", False)
            return use_server_side

    def create_cursor(self):
        if self._use_server_side_cursor():
            self._is_server_side = True
            return self.create_server_side_cursor()
        else:
            self._is_server_side = False
            return self._dbapi_connection.cursor()

    def create_server_side_cursor(self):
        raise NotImplementedError()

    def pre_exec(self):
        pass

    def post_exec(self):
        pass

    def get_result_processor(self, type_, colname, coltype):
        """Return a 'result processor' for a given type as present in
        cursor.description.
        
        This has a default implementation that dialects can override
        for context-sensitive result type handling.
        
        """
        return type_._cached_result_processor(self.dialect, coltype)

    def get_lastrowid(self):
        """return self.cursor.lastrowid, or equivalent, after an INSERT.
        
        This may involve calling special cursor functions,
        issuing a new SELECT on the cursor (or a new one),
        or returning a stored value that was
        calculated within post_exec().
        
        This function will only be called for dialects
        which support "implicit" primary key generation,
        keep preexecute_autoincrement_sequences set to False,
        and when no explicit id value was bound to the
        statement.
        
        The function is called once, directly after
        post_exec() and before the transaction is committed
        or ResultProxy is generated.   If the post_exec()
        method assigns a value to `self._lastrowid`, the
        value is used in place of calling get_lastrowid().
        
        Note that this method is *not* equivalent to the
        ``lastrowid`` method on ``ResultProxy``, which is a
        direct proxy to the DBAPI ``lastrowid`` accessor
        in all cases.
        
        """
        return self.cursor.lastrowid

    def handle_dbapi_exception(self, e):
        pass

    def get_result_proxy(self):
        if self._is_server_side:
            return result.BufferedRowResultProxy(self)
        else:
            return result.ResultProxy(self)

    @property
    def rowcount(self):
        return self.cursor.rowcount

    def supports_sane_rowcount(self):
        return self.dialect.supports_sane_rowcount

    def supports_sane_multi_rowcount(self):
        return self.dialect.supports_sane_multi_rowcount

    def _setup_crud_result_proxy(self):
        if self.isinsert:
            if not self.executemany:
                if not self._is_implicit_returning:
                    if not self.compiled.inline:
                        if self.dialect.postfetch_lastrowid:
                            self._setup_ins_pk_from_lastrowid()
                        if not self._is_implicit_returning:
                            self._setup_ins_pk_from_empty()
            result = self.get_result_proxy()
            if self.isinsert:
                if self._is_implicit_returning:
                    row = result.fetchone()
                    self.returned_defaults = row
                    self._setup_ins_pk_from_implicit_returning(row)
                    result._soft_close()
                    result._metadata = None
            else:
                if not self._is_explicit_returning:
                    result._soft_close()
                    result._metadata = None
                else:
                    if self.isupdate:
                        if self._is_implicit_returning:
                            row = result.fetchone()
                            self.returned_defaults = row
                            result._soft_close()
                            result._metadata = None
                        if result._metadata is None:
                            result.rowcount
                            result._soft_close()
                return result

    def _setup_ins_pk_from_lastrowid(self):
        key_getter = self.compiled._key_getters_for_crud_column[2]
        table = self.compiled.statement.table
        compiled_params = self.compiled_parameters[0]
        lastrowid = self.get_lastrowid()
        if lastrowid is not None:
            autoinc_col = table._autoincrement_column
            if autoinc_col is not None:
                proc = autoinc_col.type._cached_result_processor(self.dialect, None)
                if proc is not None:
                    lastrowid = proc(lastrowid)
            self.inserted_primary_key = [
                lastrowid
                if c is autoinc_col
                else compiled_params.get(key_getter(c), None)
                for c in table.primary_key
            ]
        else:
            self.inserted_primary_key = [
                compiled_params.get(key_getter(c), None) for c in table.primary_key
            ]

    def _setup_ins_pk_from_empty(self):
        key_getter = self.compiled._key_getters_for_crud_column[2]
        table = self.compiled.statement.table
        compiled_params = self.compiled_parameters[0]
        self.inserted_primary_key = [
            compiled_params.get(key_getter(c), None) for c in table.primary_key
        ]

    def _setup_ins_pk_from_implicit_returning(self, row):
        if row is None:
            self.inserted_primary_key = None
            return
        key_getter = self.compiled._key_getters_for_crud_column[2]
        table = self.compiled.statement.table
        compiled_params = self.compiled_parameters[0]
        self.inserted_primary_key = [
            row[col] if value is None else value
            for col, value in [
                (col, compiled_params.get(key_getter(col), None))
                for col in table.primary_key
            ]
        ]

    def lastrow_has_defaults(self):
        return (self.isinsert or self.isupdate) and bool(self.compiled.postfetch)

    def set_input_sizes(self, translate=None, include_types=None, exclude_types=None):
        """Given a cursor and ClauseParameters, call the appropriate
        style of ``setinputsizes()`` on the cursor, using DB-API types
        from the bind parameter's ``TypeEngine`` objects.
        
        This method only called by those dialects which require it,
        currently cx_oracle.
        
        """
        if not hasattr(self.compiled, "bind_names"):
            return
        types = dict(
            (
                (self.compiled.bind_names[bindparam], bindparam.type)
                for bindparam in self.compiled.bind_names
            )
        )
        if self.dialect.positional:
            inputsizes = []
            for key in self.compiled.positiontup:
                typeengine = types[key]
                dbtype = typeengine.dialect_impl(self.dialect).get_dbapi_type(
                    self.dialect.dbapi
                )
                if dbtype is not None:
                    if not exclude_types or dbtype not in exclude_types:
                        if not include_types or dbtype in include_types:
                            if key in self._expanded_parameters:
                                inputsizes.extend(
                                    [dbtype] * len(self._expanded_parameters[key])
                                )
                            else:
                                inputsizes.append(dbtype)

            try:
                self.cursor.setinputsizes(*inputsizes)
            except BaseException as e:
                self.root_connection._handle_dbapi_exception(e, None, None, None, self)

        else:
            inputsizes = {}
            for key in self.compiled.bind_names.values():
                typeengine = types[key]
                dbtype = typeengine.dialect_impl(self.dialect).get_dbapi_type(
                    self.dialect.dbapi
                )
                if dbtype is not None:
                    if not exclude_types or dbtype not in exclude_types:
                        if not include_types or dbtype in include_types:
                            if translate:
                                key = translate.get(key, key)
                            if not self.dialect.supports_unicode_binds:
                                key = self.dialect._encoder(key)[0]
                            if key in self._expanded_parameters:
                                inputsizes.update(
                                    (
                                        (expand_key, dbtype)
                                        for expand_key in self._expanded_parameters[key]
                                    )
                                )
                            else:
                                inputsizes[key] = dbtype

        try:
            self.cursor.setinputsizes(**inputsizes)
        except BaseException as e:
            self.root_connection._handle_dbapi_exception(e, None, None, None, self)

    def _exec_default(self, column, default, type_):
        if default.is_sequence:
            return self.fire_sequence(default, type_)
        elif default.is_callable:
            self.current_column = column
            return default.arg(self)
        elif default.is_clause_element:
            conn = self.connection
            if not default._arg_is_typed:
                default_arg = expression.type_coerce(default.arg, type_)
            else:
                default_arg = default.arg
            c = expression.select([default_arg]).compile(bind=conn)
            return conn._execute_compiled(c, (), {}).scalar()
        else:
            return default.arg

    current_parameters = None

    def get_current_parameters(self, isolate_multiinsert_groups=True):
        """Return a dictionary of parameters applied to the current row.
        
        This method can only be used in the context of a user-defined default
        generation function, e.g. as described at
        :ref:`context_default_functions`. When invoked, a dictionary is
        returned which includes entries for each column/value pair that is part
        of the INSERT or UPDATE statement. The keys of the dictionary will be
        the key value of each :class:`.Column`, which is usually synonymous
        with the name.
        
        :param isolate_multiinsert_groups=True: indicates that multi-valued
         INSERT contructs created using :meth:`.Insert.values` should be
         handled by returning only the subset of parameters that are local
         to the current column default invocation.   When ``False``, the
         raw parameters of the statement are returned including the
         naming convention used in the case of multi-valued INSERT.
        
        .. versionadded:: 1.2  added
           :meth:`.DefaultExecutionContext.get_current_parameters`
           which provides more functionality over the existing
           :attr:`.DefaultExecutionContext.current_parameters`
           attribute.
        
        .. seealso::
        
            :attr:`.DefaultExecutionContext.current_parameters`
        
            :ref:`context_default_functions`
        
        """
        try:
            parameters = self.current_parameters
            column = self.current_column
        except AttributeError:
            raise exc.InvalidRequestError(
                "get_current_parameters() can only be invoked in the context of a Python side column default function"
            )

        if isolate_multiinsert_groups:
            if self.isinsert:
                if self.compiled.statement._has_multi_parameters:
                    if column._is_multiparam_column:
                        index = column.index + 1
                        d = {column.original.key: parameters[column.key]}
                    else:
                        d = {column.key: parameters[column.key]}
                        index = 0
                    keys = self.compiled.statement.parameters[0].keys()
                    d.update(
                        ((key, parameters["%s_m%d" % (key, index)]) for key in keys)
                    )
                    return d
                return parameters

    def get_insert_default(self, column):
        if column.default is None:
            return
        else:
            return self._exec_default(column, column.default, column.type)

    def get_update_default(self, column):
        if column.onupdate is None:
            return
        else:
            return self._exec_default(column, column.onupdate, column.type)

    def _process_executemany_defaults(self):
        key_getter = self.compiled._key_getters_for_crud_column[2]
        scalar_defaults = {}
        insert_prefetch = self.compiled.insert_prefetch
        update_prefetch = self.compiled.update_prefetch
        for c in insert_prefetch:
            if c.default:
                scalar_defaults[c] = (c.default.is_scalar and c).default.arg

        for c in update_prefetch:
            if c.onupdate:
                scalar_defaults[c] = (c.onupdate.is_scalar and c).onupdate.arg

        for param in self.compiled_parameters:
            self.current_parameters = param
            for c in insert_prefetch:
                if c in scalar_defaults:
                    val = scalar_defaults[c]
                else:
                    val = self.get_insert_default(c)
                if val is not None:
                    param[key_getter(c)] = val

            for c in update_prefetch:
                if c in scalar_defaults:
                    val = scalar_defaults[c]
                else:
                    val = self.get_update_default(c)
                if val is not None:
                    param[key_getter(c)] = val

        del self.current_parameters

    def _process_executesingle_defaults(self):
        key_getter = self.compiled._key_getters_for_crud_column[2]
        self.current_parameters = compiled_parameters = self.compiled_parameters[0]
        for c in self.compiled.insert_prefetch:
            if c.default:
                if not c.default.is_sequence:
                    if c.default.is_scalar:
                        val = c.default.arg
                    val = self.get_insert_default(c)
                compiled_parameters[key_getter(c)] = val is not None and val

        for c in self.compiled.update_prefetch:
            val = self.get_update_default(c)
            if val is not None:
                compiled_parameters[key_getter(c)] = val

        del self.current_parameters


DefaultDialect.execution_ctx_cls = DefaultExecutionContext
